Barium hollandite-type ceramics have been envisaged for the immobilization of radioactive cesium. To evaluate their stability under irradiation, a hollandite ceramic of composition Ba1.16Al2.32Ti5.68O16 was irradiated with electrons at a temperature close to room temperature to simulate the effect of β- and γ-decays of cesium. Ti3+ and O2- paramagnetic defects induced by electron irradiation [V. Aubin-Chevaldonnet etal, J. Phys.: Condens. Matter 18, 4007 (2006)] were detected by electron paramagnetic resonance. As the temperature in the bulk of the hollandite waste form could reach 300 °C at the beginning of the storage, the thermal stability of these paramagnetic defects was also studied. Isothermal annealing treatments at 300 °C and isochronal annealing treatments between 50 °C and 800 °C show that the irradiation induced Ti3+ (E1 and E2 centers) and O2- (H centers) do not recombine. Instead, they partially transform during annealing, respectively, into titanyl TiO+ centers (E3 centers) at the grain surface and into paramagnetic clusters of O2- of less than 10 nm size (G2 centers), trapped in the bulk of the grains. These oxygen-rich aggregates could prefigure the formation of molecular oxygen observed in electron irradiated glasses.